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3 years ago

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Which is an example of a chemical change? A) glass melts in a furnace B) liquid water boils into steam C) newspaper decays in a

landfill D) rain condenses and falls from water vapor in a cloud

2 answers:

Anestetic [448]3 years ago

8 0

MrPsychotic sorry i meant to give you five stars but yea da answer is c

coldgirl [10]3 years ago

3 0

I believe your answer is C.

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An electron has a mass of 9.1x10-31 kg. What is its momentum if it is travelling at a speed of 3.5x106 m/s?

galben [10]

Answer:

3.19*10^-24

Explanation:

the equation to find momentum is p=mv so you just multiply the mass times velocity

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3 years ago

GIVING BRAINLIEST PLEASE HELP!!

maxonik [38]

Answer:

B

Explanation:

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3 years ago

Read 2 more answers

A capacitor is being charged from a battery and through a resistor of 10 kΩ. It is observed that the voltage on the capacitor ri

swat32

Answer:

$C = 2.48 \times 10^{-4} Farad$

Explanation:

As per the equation of voltage on capacitor we know that

$V = V_{max}(1 - e^{-\frac{t}{\tau}})$

now we know that voltage reached to its 80% of maximum value in 4 second time

so we will have

$0.80 V_{max} = V_{max}(1 - e^{-\frac{4}{\tau}})$

$0.20 = e^{-\frac{4}{\tau}}$

$-\frac{4}{\tau} = ln(0.20)$

$-\frac{4}{\tau} = -1.61$

$\tau = 2.48$

as we know that

$\tau = RC$

$(10 k ohm)(C) = 2.48$

$C = 2.48 \times 10^{-4} Farad$

4 0

3 years ago

A 0.9 kg ball attached to a cord is whirled in a vertical circle of radius 2.5 m. Find the minimum speed needed at the top of th

lapo4ka [179]

Answer:

The minimum speed needed at the top of the circle so that the cord remains tensioned and the ball's path remains circular is approximately is 9.903 meters per second.

Explanation:

By the Principle of Energy Conservation we understand that the minimum speed needed by the ball is that speed such that maximum height reached is equal to the diameter of the vertical circle, that is:

$K =U_{g}$ (1)

Where:

$K$ - Translational kinetic energy, measured in joules.

$U_{g}$ - Gravitational potential energy, measured in joules.

By definitions of translational kinetic and gravitational potential energies, we expand the equation above and clear the initial speed of the ball:

$\frac{1}{2}\cdot m \cdot v^{2} = m\cdot g\cdot h$

$v = \sqrt{2\cdot g\cdot h}$ (2)

Where:

$m$ - Mass, measured in kilograms.

$v$ - Initial speed, measured in meters per second.

$g$ - Gravitational acceleration, measured in meters per square second.

$h$ - Maximum height of the ball, measured in meters.

If we know that $g = 9.807\,\frac{m}{s^{2}}$ and $h = 5\,m$ , then the initial speed of the ball is:

$v = \sqrt{2\cdot \left(9.807\,\frac{m}{s^{2}} \right)\cdot (5\,m)}$

$v\approx 9.903\,\frac{m}{s}$

The minimum speed needed at the top of the circle so that the cord remains tensioned and the ball's path remains circular is approximately is 9.903 meters per second.

3 0

3 years ago

A cube of copper was found to have a mass of 630 g. What are the dimensions of the cube? (The density of copper is 8.94 g/cm3.)

raketka [301]

Answer:

Density = mass/volume

Volume of cube = mass/density

630g/8.94 = 70.5cm^3 (3s.f.)

Since it is a cube, its dimensions of Length x breadth x height=volume

Take 70.5 amd cube root it

$\sqrt[3]{70.4697986577)$

=4.13 (3s.f)

hence , it would be 4.13 x 4.13 x 4.13 to find the volume

Hence, the answer would be 4.13cm(3s.f.)

3 0

3 years ago